Star Wars' Death Star was supposed to be the Empire’s replacement for Darth Vader. One of the most recognizable elements of the Star Wars universe, the Death Star has been a mainstay in the franchise's lore, either appearing or being referenced in everything from the first Star Wars movie to the Andor Disney+ TV show. The Empire's battle-station was even the focus on the first Star Wars anthology movie, Rogue One: A Star Wars Story.
Between special stormtroopers like the Death Troopers and battle-stations of the size of a moon, the Empire was always looking for new ways to upgrade its arsenal. At the same time, Palpatine commanded his own legion of Inquisitors, former Jedi who had fallen to the dark side but were not Sith, led by Darth Vader. However, had the first Death Star not been destroyed, the Empire might have been quick to replace Darth Vader with its new battle station.
How The Death Star Shifted The Star Wars Galaxy’s Power Balance
Palpatine was the greatest Sith Lord of all time, but he knew even he couldn't rule the entire galaxy without the help of much of the Galactic Republic's structure - repurposed and transformed into the Empire. The Senate, for example, continued to exist - except it was now an Imperial Senate. Palpatine only closed the Imperial Senate once the Death Star was complete, because the balance of power had changed. The Death Star could eliminate entire planets in a split second, meaning the Emperor could now rule through fear.
Star Wars has openly admitted this is why the Death Star's destruction was bad for Palpatine. In Kieron Gillen and Salvador Larroca's Darth Vader #1, the Emperor was furious Darth Vader failed to protect the Death Star. "Now, we no longer have the Senate to hold order," the Emperor fumed. "We do not have the Death Star to force it. Our greatest weapon is gone, our production is in ashes. We are besieged. In all these years, we have never skirted closer to disaster..."
A Fully Operational Death Star Would’ve Made Darth Vader Obsolete
There is an irony in Palpatine's holding Darth Vader responsible for the destruction of the Death Star; it is that it could easily have been his replacement. This was acknowledged by George Lucas himself, in an interview with Rolling Stone. According to Lucas, “by the time the Death Star is finished”, the battle-station gave the Empire a “bigger, better suit than Darth Vader”. Lucas noted that, in a comparison between a mighty battle-station and dark side Force powers most Imperials didn't comprehend (and many didn't believe in), the Empire would have “no question” regarding which one to choose. Essentially, the Death Star was the Empire’s replacement for Darth Vader.
It's easy to see why even Palpatine would have thought this. If the Empire could now destroy entire planets without having to deploy a single stormtrooper, then Force-sensitive hunters like the Inquisitors and Darth Vader himself became obsolete. There was really no problem the Death Star could not solve for Palpatine – be it a rebel cell or a potential Jedi. For example, had Palpatine somehow discovered that Yoda was hiding in Dagobah before the Death Star was destroyed, Darth Sidious could have killed his greatest Jedi rival without having to ignite a lightsaber. Darth Vader was an effective problem-solver for Palpatine and the Empire, but the Death Star would have been far more effective.
Why The Empire Never Really Respected Darth Vader
According to George Lucas, the Imperials were aware that “the Emperor is the final world”, and that they did not really have to worry about Palpatine’s lackey. Granted, Darth Vader using the Force to choke an Imperial in A New Hope comes off as scary for those in the room, yet they know that there is not much Darth Vader can do outside the Emperor’s orders. Grand Moff Tarkin, for example, did not fear Darth Vader at all, as the character responded directly to Emperor Palpatine. In the eyes of the Empire, Darth Vader was a glorified bounty hunter.
That said, the lower ranks of the Empire did fear Darth Vader. The Empire Strikes Back features several moments in which Darth Vader scares the crew aboard his Star Destroyer, as seen in the classic scene in which Vader Force chokes Admiral Ozzel despite them being in two different places. The Empire Strikes Back helped redefine Darth Vader as a major Star Wars villain in his own right, but Return of the Jedi reminded audiences Vader was never the one in charge. Darth Vader was an important asset, but replacing the Death Star was even more important – at least from the Empire's perspective.